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Firewall builder ip address table3/1/2023 ![]() Keep state will also allow ICMP packets related to a TCP or UDP session through. Pass in proto udp from any to any port = 53 keep state This can be effectively replaced with the following: Which allows through a LOT of unwanted packets. ![]() Pass in proto udp from any port = 53 to any port > 1024 Pass out proto udp from any port > 1024 to any port = 53 For example, the following could be used for DNS clients: Keep state automatically matches packets going in the reverse direction (usually out) or on other interfaces without needing explicit rules.įor UDP, it will automatically allow packets in which are the "reverse" of packets that have already been allowed through, without needing to allow too many packets through. Pass in quick proto tcp from any to any port = smtp flags S keep state Pass out proto tcp from any port = smtp to any Pass in quick from any to any port = smtp flags S What it does is allows you to only allow TCP packets through your firewall which are recognised as being part of an established connection rather than just arbitary TCP packets which can be used to perform "stealth scanning". Can I have variables in my ipf.conf/nf?įirst, yes, it is useful. ![]()
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